On the equal-mass limit of precessing black-hole binaries. (1st March 2017)

• Record Type: Journal Article
• Authors: Gerosa, Davide; Sperhake, Ulrich; Vošmera, Jakub
• Is Part Of: Classical and quantum gravity. Volume 34:Number 6(2017:Mar.)
• Publication Date: 2017-03-01
• Subjects: black holes -- gravitational waves -- post-Newtonian theory; Quantum gravity -- Periodicals; Gravitation -- Periodicals; Relativity (Physics) -- Periodicals; Space and time -- Periodicals; Periodicals; 521.1
• DOI: 10.1088/1361-6382/aa5e58
• Languages: English
• ISSNs: 0264-9381

Abstract

Abstract: We analyze the inspiral dynamics of equal-mass precessing black-hole binaries using multi-timescale techniques. The orbit-averaged post-Newtonian evolutionary equations admit two constants of motion in the equal-mass limit, namely the magnitude of the total spin S and the effective spin ξ . This feature makes the entire dynamics qualitatively different compared to the generic unequal-mass case, where only ξ is constant while the variable S parametrizes the precession dynamics. For fixed individual masses and spin magnitudes, an equal-mass black-hole inspiral is uniquely characterized by the two parameters ( S, ξ ) : these two numbers completely determine the entire evolution under the effect of radiation reaction. In particular, for equal-mass binaries we find that (i) the black-hole binary spin morphology is constant throughout the inspiral, and that (ii) the precessional motion of the two black-hole spins about the total spin takes place on a longer timescale than the precession of the total spin and the orbital plane about the total angular momentum.